Central WI Forest Health

The Wisconsin Department of Natural Resources has released updated guidelines to aid woodland owners and managers in managing ash stands in light of the invasive emerald ash borer (EAB). The guidelines that became effective on January 1, 2019 reflect new research, increased pest detections and the anticipated transition to a statewide EAB quarantine (which occurred in March 2018).

The silvicultural guidelines are intended to help make informed stand-level decisions regarding management of stands that are not yet infested by EAB and stands that are already impacted by the tree-killing beetle. They should be used along with other materials, including best management practices and other guidance documents, to develop appropriate management plans.

The revised guidelines include recommendations to:

Implement management plans as soon as practical, across all of Wisconsin, to reduce a stand’s ash component to no more than 20%. More management options are likely to be available by taking immediate action

Utilize merchantable ash before trees are infested or killed. It may be appropriate to retain some live ash on site for ecological benefits, species diversity, wildlife habitat, temporary cover or seed production

The guidelines also place a greater emphasis on assessing stand and site conditions before making management decisions. The document offers stand management alternatives for both upland and lowland stands, while recognizing that conversion of lowland ash stands to other forest types will be impractical in many cases.

The Wisconsin Department of Natural Resources has released updated guidelines to reduce the risk of introduction and spread of Heterobasidion root disease (HRD) in Wisconsin through preventive stump treatments. The revised guidelines became effective on January 1, 2019, and a professionally designed version will be available soon. Woodland owners are strongly encouraged to work with a professional forester to make management decisions about HRD and preventive stump treatments.

Heterobasidion root disease is one of the most destructive diseases affecting conifers in the Northern Hemisphere. In Wisconsin, HRD is most commonly found in pine and spruce plantations. Infection by the wood-decaying Heterobasidion irregulare fungus kills living tissues and leads to growth loss and tree mortality. Spores landing on a fresh cut pine or spruce stump will infect that stump and root system and spread via root contact to neighboring trees, killing them as it invades their root systems. This pattern of spread creates pockets of dead and dying trees that expand outward. Growth reduction of trees leads to economic losses for plantation owners, and mortality of trees, including seedlings and saplings, has long-term implications for future stand composition and management.

The HRD stump treatment guidelines are designed to help make decisions about the use of preventive stump treatments when harvesting a stand. These treatments limit disease introduction by preventing fungal spores from developing on the exposed surfaces of newly cut stumps.

Pesticides used in stump treatments can be applied using logging equipment (blue mist exiting through nozzles in saw bar) or backpack sprayer.

Stump treatments are typically recommended between April 1 and November 30 if a stand is within 25 miles of a known HRD infection site and the stand is more than 50% pine and/or spruce. However, there are other factors to consider when deciding whether to use the preventive stump treatments. Certain situations when you may not need to treat stumps, referred to as “Exceptions” and “Modifications” in the guidelines, consider variables such as economic feasibility, landowner risk tolerance, unexpected weather patterns and future desired stand composition. Highlights of the revised stump treatment guidelines include:

Timing of treatments and general distance recommendations did not change from older guidance

Addition of spruce as a species recommended for stump treatment

Additional Exceptions and Modifications where treatment may not be necessary

For private landowners with a higher risk tolerance, a 6-mile radius from known infection sites can be considered when evaluating whether to apply treatments

Even if a stand is considered at low risk for HRD infection, woodland owners should carefully consider the potential impacts to their stand if preventive treatments are not used and HRD becomes established

Along with the guidelines, a web-based HRD map viewer has been launched. This interactive map displays confirmed HRD locations and 25-mile and 6-mile radius buffers around HRD locations. The purpose of this map is to help users determine whether a stand is within either the 25 or 6-mile buffers where stump treatments are recommended. You can enter an address or GPS location, turn map layers on and off, and zoom in and out to an area of interest.

The Forest Health Annual Report summarizes notable impacts pests, diseases and weather on the health of Wisconsin’s forests. The report is a collaborative product written by DNR forest health specialists from around the state. It outlines the damage and spread of both native and invasive pests and diseases during that year and puts these into context of observations from previous years. Management programs and their results are also described. Highlights from the 2018 annual report include:

American beech with resistance to disease-causing scale insect entered into a breeding program for species conservation and reintroduction

Confirmation of jumping worms in northern counties

Biological control of emerald ash borer

Closure of the state gypsy moth suppression program

Innovation in survey of the invasive plant lesser celandine

Dieback and mortality in balsam fir caused by freezing weather in April followed by unseasonably hot temperatures in early May

The 2018 report and others dating back to 2003 are available on the forest health publications page. Historical reports dating back to 1951 are archived and available upon request. Contact Marguerite Rapp at marguerite.rapp@wisconsin.gov for more information on the archived reports.

The small brown blotches on the underside of these needles are an invasive species found on some holiday decorations purchased from chain stores in 2018. Help prevent the spread of elongate hemlock scale by properly disposing of wreaths, swags and other potentially infested materials. (Photo credit: WI Dept. of Ag, Trade & Consumer Protection)

Please remember to properly dispose of wreaths, trees and other holiday decorations from chain stores that may be infested with an invasive insect.

If you purchased any holiday wreaths, swags, boughs and other arrangements from chain stores, please dispose of them by burning or bagging them and putting them in the trash as they may be infested with an aggressive invasive insect that can harm Wisconsin’s native forests, Christmas tree farms, and even ornamental conifers in your yard.

During this recent holiday season, Department of Agriculture, Trade and Consumer Protection (DATCP) inspectors found an invasive insect pest from Asia called elongate hemlock scale (EHS) on holiday wreaths, swags and boughs, and in arrangements of evergreen boughs in hanging baskets, porch pots, mugs and sleighs.

These items came from suppliers in states where EHS is already established. This insect poses a risk to Christmas tree fields as well as native and ornamental coniferous trees in Wisconsin. To prevent the introduction of EHS to Wisconsin, DATCP officials are asking those who purchased the listed decorative items from chain stores in 2018 to properly dispose of them.

The Wisconsin DNR’s forest health team received funding to trap for non-native beetles in 2018. This project was funded by the US Forest Service through an Early Detection and Rapid Response (EDRR) grant. The project is complete, and we happily share that we did not find any non-native beetles!

The Forest Service periodically provides funding to states to trap for non-native bark and ambrosia beetles. The goal of trapping is to detect, delimit and monitor newly introduced exotic beetles and to quickly assess and respond to newly detected infestations.

We placed traps at 12 high-risk sites in Jefferson, Waukesha, Milwaukee, Racine, Manitowoc, and Brown counties. Sites were selected in collaboration with the Wisconsin Department of Agriculture, Trade and Consumer Protection and were based on proximity to large commercial port entries on Lake Michigan or recycling facilities for pallets and other waste packaging. Three Lindgren funnel traps (12 funnels stacked to look like a tree trunk) and lures were assembled at each site and checked every two weeks between early May and early August. Specimens collected from the traps were sent to a Forest Service taxonomist for identification.

Oak wilt (OW) was confirmed for the first time in Bayfield and Douglas counties and in 16 new northern townships in 2018. The new OW infections occurred on a range of properties, including county, tribal, private, U.S. Forest Service and Board of Commissioners of Public Lands. Wisconsin Department of Natural Resources (DNR) forest health staff are working proactively with affected property managers and landowners to address these infections and prioritize disease prevention and detection in the future.

The greatest risk of overland transmission in northern Wisconsin is from April 15 to July 15, when fungal spores readily infect open wounds. Most of these new cases occurred during this time frame due to stem and branch damage. The primary causes of damage were roadside brush clearing, pruning, lot clearing and storm-caused branch breakage. Fungal spores may have come from diseased oak firewood and unprocessed wood recently transported into these areas.

OW disease center. Oak on far left was infected through belowground root contact with tree damaged in lot clearing (far right). Dairyland Township, Douglas County (photo taken by Paul Cigan).

If oak wilt is present in or within 6 miles of the county where you manage oak, your management activities may be affected by seasonal harvesting restrictions to reduce OW introduction and impact. Read DNR’s oak harvesting guidelines for more information and refer to the list below of new 6 square mile blocks by township and county to see if OW has been detected near your property.

Heterobasidion root disease (HRD), formerly known as annosum root rot, was recently found in Monroe County for the first time in the town of Little Falls. With this detection, HRD is now known to occur in 28 Wisconsin counties.

HRD distribution map. Counties where HRD is present are shown in blue with most recently confirmed county shown in dark blue.

Fruiting bodies of the pathogen, Heterobasidion irregulare, were found on dead overstory red pine and both live and dead white pine saplings in the Big Creek Fishery Area. The 20-acre stand was a red pine plantation established in 1958 and last thinned in 2012. Wood samples were collected to isolate and identify the pathogen through microscopic identification at the Forest Health Lab in Fitchburg.

Based on this new find, a number of townships were added to the 25-mile buffer zones used in determining appropriate management activities according to the HRD Management Guide. There will be a one-year grace period for implementation of the guide in these townships.

The Forest Health Program has records of all confirmed HRD detections. If you suspect this disease is present in a stand, contact your regional forest health specialist.

Wisconsin Pesticide Applicator Training (PAT) Program with University of Wisconsin Extension is offering one training session for Forestry (Category 2.0) in 2019. The training is a one-day indoor session to review the materials in the training manual. A certification exam will be administered at the end of the day by Wisconsin Department of Agriculture, Trade and Consumer Protection.

The PAT Forestry training day is scheduled for January 24, 2019 at the Marathon County Extension Office in Wausau. Preregistration is required and costs $30. For more information and to register, visit the Pesticide Applicator Training website.

We do NOT have Asian longhorned beetle (ALB) in Wisconsin at this time, but it’s good to be on the lookout for it. Every year folks submit reports of insects that they suspect to be ALB, but to date they have always been confirmed as the native whitespotted sawyer(sometimes called pine sawyer), which attacks stressed conifers rather than the maple and other hardwood species preferred by ALB. If you find a beetle that you suspect to be ALB, please collect the beetle, take some pictures, and send them to your forest health specialist, or to the University of Wisconsin Insect Diagnostic Lab for identification.

Asian longhorned beetle is a large beetle. They are smooth and shiny black with white spots and blotches on their wing covers. Photo by Joe Boggs, Ohio State University, bugwood.org.

ALB can be a very destructive pest. It is typically introduced, unintentionally, to new areas via wooden pallets, wood packing materials, or firewood. The Don’t Move Firewood website has some great tips for safe transport of firewood, how to find firewood locally, as well as a list of other invasive insects and diseases to be aware of when buying or using firewood.

USDA APHIS, which conducts eradication efforts wherever ALB is found, recently announced that an area of Ohio was officially ALB-free, and the quarantine was subsequently removed. Earlier this year in March, a separate area of Ohio was also declared ALB-free. That leaves just one area of Ohio with ALB quarantines still in effect. Eradication of ALB can take decades to complete and involves extensive efforts including tree removal and chemical treatments. States with current ALB quarantines include: Massachusetts, New York and Ohio.

For more info on ALB, check out the USDA APHIS ALB webpage, and as always, please let us know if you think you have come across a forest health concern, including ALB.

Invasive brown marmorated stink bugs (BMSB) are now well established and reproducing in southern and central Wisconsin. This fall we are getting our first reports of large numbers of BMSB gathering on the sides of houses looking for places to overwinter. This problem will continue to get worse as stink bug populations increase and their range expands. Damage to important crops, ornamental plants and trees will also be a major concern. BMSB is known to feed on a wide variety of plants including apples, tomatoes, corn, soybeans, silver maple and walnut.

Researchers are working on ways to manage the pesky bugs. One new method being explored is hanging black netting soaked in insecticide at locations where the bugs congregate, such as doors on the north and east sides of structures.

Samurai wasps are another promising lead. These stink bug-killing wasps found their way into the U.S. on their own over the past few years, but researchers are also working with lab-reared samurai wasps that they hope to release. Samurai wasps parasitize the eggs of BMSB but do not sting humans or other animals.